Crystal structures, orientations and magnetic properties of Ni-Fe co-deposits obtained from sulfamic acid baths were studied by X-ray diffractiometry and hysteresis loop measurements. The following results were obtained: (1) The orientation was determined by the ratio of intensity of peak lines of X-ray in Ni-Fe co-deposit to that in the powdered sample. The strength of orientation was assumed to be the value calculated by the following equation: The strength of orientation=A/B where A=The ratio of the intensity of strongest peak of X-ray diffraction lines to the intensity of the second peak of those in the electrodeposited layer. B=The above ratio of X-ray diffraction lines of the same plane indices in the powdered sample. (2) In a body-centered cubic lattice, the strength of orientation in (110) increased with the increase of current density. The strength of orientation was less at pH=2.0 and greater at 50°C in both of body-centered and face-centered lattices. (3) In general, coercive force of the films increased, but saturation magnetization of the films decreased with the increase in nickel content of the films.

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Anodizing of aluminum in aluminate solutions was studied from the viewpoints of film structure and breakdown phenomena. It was shown by scanning electron microscopy and impedance measurements that the oxide galvanostatically formed in solutions more dilute than 0.1mol NaAlO₂ consisted of two layers; an underlying barrier type oxide layer and a thick upper of aluminum hydroxide. The measurements of dependence of film impedance on frequency further showed the evidences of composite structure. The formation of the upper layer was explained in terms of the precipitation of aluminate anions caused by protons generated on the oxide/solution interface and field-assisted dehydration of the resultant hydroxide on the barrier layer, which was suggested from the impedance characteristics. It was demonstrated that aluminate solution was a very unique and useful forming solution for the barrier layer coating. The sparking voltages of the oxide film formed in aluminate were higher than those of the film in usual electrolytes such as borate, and the upper layer was considered to be a protective layer against breakdown. This remarkable effect was discussed in connection with the degree of dehydration of the upper layer. It was further observed that the thickness of barrier layer increased and that of upper layer decreased by the aging at a constant voltage for a few hours, which means as possibility that a part of the upper layer was converted into a barrier type oxide during the aging.

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In this study, an anodic oxidation was made by electrolysis by using a sintered body of aluminum prepared in nitrogen atmosphere as anode and ammonium dihydrogen phosphate as electrolyte A dielectric element thus obtained was made into a solid electrolytic condenser by coating with manganese dioxide (MnO₂) as semiconductor. That is: a solid electrolytic condenser of sintered sluminum was prepared. Experiments were conducted to examine the effects of particle size of aluminum powder and compacting pressure on electric characteristics of the condenser. The particle size in the experiments was of 4 kinds: 20, 35-150, 150-200, and 200 mesh, and the compacting pressure applied was 0.1 and 0.2t. The capacitance at 120Hz was assumed to be 100 as a standard and the ratio of capacitance at each frequency was considered for examination. As the results of experiments, it was observed that the capacitance ratio at each frequency was smaller and the value of tan δ was larger with the decrease in particle size of aluminum powder, and there were little differences between the effects of 0.1 and 0.2t of compacting pressure.

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As for the electrodeposited silver obtained from cyanide baths for silver plating, the relation between the rectified waves of power source and the hardness of deposited silver was examined. The rectified waves used were smoothed direct current, single-phase full-wave rectification, and single-phase half-wave rectification; and their form factors were 1.00, 1.22, and 1.73, respectively. The results obtained were as follows: (1) The hardness of brightless silver platings, which had been obtained under low current density, decreased with the increase of form factor. However, no relation was observed between hardness and form factor when current density was not lower than 1amp./dm². (2) The hardness of bright silver platings, which had been obtained under current density of 1-3amp./dm², decreased with the increase of current density. However, no relation was observed between hardness and from factor when current density was lower than the values in the above range. (3) The hardness of brightless silver platings decreased with the rise of bath temperature. (4) The hardness of bright silver platings, which had been obtained at considerably low temperatures, decreased with the increase of form factor. However, no relation was observed between hardness and form factor at bath temperatures of not lower than 35°C. It was shown by the above facts that the balancing between crystal growth rate and electrodeposition rate depended upon bath temperature.

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Studies were made on the self-regulation of fluoride concentration in the chromium plating baths saturated with CaF₂, to which Ca²⁺ had been added. The following results were obtained: (1) Because of the character of weak acid salt, CaF₂ had a very higher solubility in a solution of low pH value such as the chromium plating bath than in the aqueous solution. (2) By the addition of Ca(OH)₂ to the chromium plating bath, the concentration of fluoride was optionally self-regulated in the bath. (3) The decrease in the solubility of fluoride complied with the “effects of common ion” when the change in value of pH was considerably slight. (4) For instance, the solubility of CaF₂ was 5.5g/l in a chromium plating bath containing 250g/l of CrO₃, which would be a self-regulating bath for fluoride by the addition of a small amount of Ca(OH)₂. The solubility of CaF₂ was 2.5g/l in a low concentration chromium plating bath containing 50g/l of CrO₃. Since the optimum concentration of CaF₂ in this solution is 0.6g/l, 20g/l of Ca(OH)₂ should be added for the preparation of self-regulating bath; however, under such conditions, chromium deposits were of coarse structure owing to the generation of dichromate.

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The cemented carbides of tungsten-carbide base were treated with chromium diffusion process for the purpose of improving their oxidation resistance and corrosion resistance. The results obtained were as follows: (1) As for a solid diffusion process for cemented carbides of tungsten-carbide base, chromium powder method was more suitable as compared with chromium chloride method. (2) As for WC-Co alloys, chromium was mainly diffused in the cobalt binder phase. (3) The mechanical properties of cemented carbides of tungsten-carbide base were slightly deteriorated by chromium diffusion process. (4) The oxidation resistance of WC-Co alloys at high temperatures was markedly improved by chromium diffusion process. (5) The corrosion resistances of these carbides in the air of 90% relative humidity and in 10% HNO₃ or 10% H₂SO₄ were improved by chromium diffusion process.

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Inhibition effects and mechanism of benzotriazole (B.T.A.) on corrosion of Cu in NaCl, NaClO₄, and HClO₄ solutions were studied by potentiostatic polarization curves, electrical double layer (e.d.l.), and capacity-electrode potential curves; and by the relation between inhibition efficiency (P) determined by immersion test and degree of surface coverage (Q) obtained from e.d.l. capacity in Cu-NaCl-B.T.A. system. Each of the values of P and Q were measured as functions of B.T.A. concentration (m). The results obtained were as follows: (1) The inhibition effect of B.T.A. in Cu-NaCl system depended on its concentration and electrode potential. In anodic potential region, it was found that B.T.A. had little effects in low concentration, but a good inhibition effect was obtained in high concentration, because B.T.A. -Cu complex was formed and adsorbed on the surface. Whereas, in cathodic potential region, inhibition effects were found in both of low and high concentrations, owing to chemisorption of B.T.A. on the surface with a lone electron-pair of N-atom. (2) However, in Cu-NaClO₄ system, it was observed that B.T.A. in low concentration had good inhibition effects in anodic and cathodic potential regions. (3) It was also found that B.T.A. had little inhibition effects in acid solutions such as of HClO₄, but it had maximum effects in neutral solutions such as of NaCl and NaClO₄. (4) The P-m and Q-m curves obtained in Cu-NaCl-B.T.A. system were typical Langmuir's adsorption isotherms. Proper linear correlation was observed between P and Q, but the correlation coefficient varied according to the range of B.T.A. concentration.

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